Exam 2 -Body Cavities and Mesenteries

Question 1

What is the initial space within the embryo?

Answer 1

The intraembryonic coelom

Question 2

What occurs during the longitudinal folds?

What occurs during the transverse fold?

Answer 2

• The cardiogenic area is shifted into the thoracic area.
• Incorporation of the yolk sac and eventual formation of the gut tube, body cavity formation, connect to the yolk sac reduced to a stalk

Question 3

What lines the inside of the intra-embryonic coelom (body cavity)? What is this divided into and what are there innervations?

Answer 3

• Lateral plate mesoderm
• Divided into the somatic and splanchnic mesoderm. The somatic is innervated by GSA fibers and the splanchnic mesoderm is innervated by GVE

Question 4

What structures does the intraembryonic coelom go on to form?

Answer 4

• In the thorax is forms the pericardial cavity; in the pericardioperitoneal cavities it form the pleural cavities; in the abdomen and pelvis forms the peritoneal cavity.
  Essentially is the body cavity outside the gut tube and organs.

Question 5

What structures does the coelomic epithelium (lining the intraembryonic coelom) give rise to?

Answer 5

• Smooth muscle and connective tissue of tubes (mesoderm), cardiac muscle, sustentacular cells that surround the germ cells, and the epithelium of the reproductive tracts

Question 6

What are the 3 types of ventral wall defects that we need to know, that occur due to a failure of body folding or incomplete development?

Answer 6

• Cleft Sternum
• Ectopia Cordis
• Omphalocele

Question 7

The septum transversum is originally a thickened mass of what type of tissue? What 2 areas does this structure eventually divide?What is the innervation of this area?

Answer 7

• Thickened mass of lateral plate mesoderm
• Separates the thoracic cavities and the abdominal cavities
• C3, C4, C5

Question 8

What does the rapid growth of lung buds result in?

Answer 8

• Results in the splitting of body wall mesoderm into the definitive body wall and the pleuropericardial membranes (contain the common cardinal veins and phrenic nerves)

Question 9

The pleuropericardial folds are covered with somatic mesoderm and give rise to?

Answer 9

• Somatic layer of serous pericardium
• Fibrous Pericardium
• Mediastinal Pleura

Question 10

What structures form the diaphragm?

Answer 10

Septum transversum, Pleuroperitoneal membranes, Paraxial mesoderm, dorsal mesentery

Question 11

What does the septum transversum form?

Answer 11

Central tendon of the diaphragm

Question 12

What does the Pleuroperitoneal membranes form?

Answer 12

• 2 outgrowths of the body wall that contact the septum transversum

Question 13

What does the paraxial mesoderm form?

Answer 13

• Forms most of the muscle of the diaphragm

Question 14

What does the dorsal mesentery form?

Answer 14

• forms the right and left crura ( from the esophagus)

Question 15

What is the main cause of the hernia of Bochdalek (aka congenital diaphragmatic hernia)?

• Where is it more common?
• What causes death?

Answer 15

• failure of the pleuroperitoneal membrane to close the pericardioperitoneal canal.
• most common on the left because its much larger and closes later.
• pulmonary dysfunction

Question 16

Where is the defect in an esophageal hernia?

Answer 16

• Defect is in the right crus with a short esophagus causing the stomach to be constricted at the level of the diaphragm and possibly herniate into thorax.

Question 17

What is the deficit in a parasternal hernia?

Answer 17

• deficit between the sternal and costal heads of the diaphragm and may go undetected until the child is several years old.

Question 18

What does mesentery provide a pathway for?

Answer 18

• blood, nerves, and lymphatics

Question 19

In the embryo where does the dorsal and ventral mesenteries run?

Answer 19

• Dorsal mesentery: runs the length of the gut tube

- Ventral mesentery: runs from the diaphragm to the yolk sac (due to umbilical cord disturbance)

Question 20

What types of cells are the spleen derived from?

What weeks is the spleen an hematopoietic organ?

Answer 20

• Mesenchymal cells (mesoderm)

- Between 12-24 weeks then functions mainly as a lymphoid organ

Question 21

What are the derivative of ventral mesentery?

Answer 21

• [all attachmented to the liver] Lesser omentum, falciform ligament, coronary ligaments of the liver, right and left triangular ligaments

Question 22

What is the epiploic foramen of winslow?

What occurs to the greater sac during development that reduces the volume of the lesser sac?

Answer 22

• is a communication from the greater sac (peritoneal cavity) to the lesser sac (omental bursa)
• Greater sac fuses

Question 23

What is the definition of retroperitoneal?

Answer 23

• organs covered only on one surface with peritoneum and thereby immobile

Question 24

What are the Peritoneal organs?

Answer 24

• Stomach, spleen, parts 1 and 4 of the duodenum, jejunum, and ileum, transverse sigmoid colon

Question 25

What are the primary retroperitoneal organs?

Answer 25

• Organs that nerve had a mesentery: kidneys, ureters, bladder, aorta, IVC, etc.

Question 26

What are the secondary retroperitoneal organs?

Answer 26

• Mesentery as an embryo that became retroperitoneal –> duodenum parts 2 and 3, ascending and descending colon, rectum, pancreas, gallbladder, and liver

Question 27

What is the mnonenic for retroperitoneal organ?

Answer 27

• SADPUCKER
  (S- suprarenal glands; A- Aorta/IVC; D- Duodenum[2nd and 3rd segments]; P- pancreas; U-ureters; C- colon (ascending and descending only); K- kidney; E- esophagus lower 2/3; R-rectum lower 2/3.
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